This invention relates to a method of depyrogenating products and materials used in the biomedical field.
In the preparation of certain products and materials used in the biomedical field, the problem of contamination with pyrogens (endotoxins) is ever present.
Pyrogens are lipopolysaccharides (LPS) derived from the outer cell wall of gram-negative bacteria. They are toxic materials which are known as "endotoxins" to distinguish them from toxic substances synthesized and excreted by the intact bacterium. Pyrogens have numerous biologic activities which include the production of fever, activating of clotting mechanisms and induction of shock. Consequently, it is essential that pyrogenic substances be removed or inactivated and the causative bacteria be rendered innocuous by sterilization or other such treatment of the final biomedical product or material.
Prior methods for inactivation of pyrogens comprise extensive and rigorous treatment with heat, acid or alkali, filtration of insoluble pyrogens or removal by adsorption with gels, ion-exchange resins and various other such adsorbent materials. Most of these methods are burdensome, time-consuming and costly.
Further background information on the properties and effects of pyrogens can be had by reference to a paper by Elizabeth Work, entitled "Production, Chemistry and Properties of Bacterial Pyrogens and Endotoxins" in "Pyrogens and Fever", Ciba Foundation Symposium, 1971, pp. 23-47, edited by Wolstenholme and Birch, published by Churchill Livingstone; and a paper by D. C. Morrison and R. J. Ulevitch, entitled "The Effects of Bacterial Endotoxins on Host Mediation Systems" in Amer. J. Pathol. 93(2), 527-601 (1978).
Recently, in said copending application, Ser. No. 194,263, the present inventor disclosed a method of depyrogenating proteinaceous biological and pharmaceutical products. The method comprises treating said products by prolonged contact with a solution or suspension of a non-denaturing amphiphile, precipitating the proteinaceous product with a protein precipitant, and then separating from the precipitate the supernatant which contains the amphiphile and the dissociated or disaggregated endotoxin. Certain products and materials used in the biomedical field due to their non-proteinaceous nature or to their physical structure do not lend themselves well to precipitation with protein precipitants. That is, they are essentially non-precipitable by such methods or are preferably separated by means other than precipitation. In such cases, it is preferred to separate and remove the amphiphile and the dissociated or disaggregated endotoxin from the biomedical product or material by the improved methodology disclosed and claimed herein.